The point of departure of the roller grate of the present invention is the state of the art known from SU 1 756 741 A1. That document describes a roller grate wherein every intermediate component comprises a system of stationary bars with gaps between them. Accommodated below the intermediate components are air boxes. Air is supplied to the boxes by a fan that is independent of the primary-air system. The particular object is to improve burn-up.
A roller grate wherein air is blown into a nip or space between through bar-like intermediate components is also known from German Patent 600 546. The bar-like components are in two parts. The two are moved relative to one another and to the rollers by a cam. The motion is intended to poke the bed of fuel resting thereon. The intermediate components obtain their air from the adjacent rollers. The streams of air blown in by way of the intermediate components are accordingly component streams of the primary air.
As far as is known, the approaches suggested in these two documents have never been applied to garbage incinerators. The space between the adjacent rollers in the roller-grate combustion systems currently known and being built are bridged over by intermediate components in the form of slender strips, usually called strippers. Specific examples of such strips are described in German 3 420 020 C1 and German 4 300 636 C1 for instance. Supplemental air is not supplied to the nips or spaces between the rollers. All of the primary air supplied to the fuel bed arrives through the surfaces of the rollers.
The layer of fuel in the vicinity of the nip or spaces is considerably thicker than in the areas where it rests against the rollers. The fuel also has a tendency to become denser in the vicinity of the gaps, where there the material is finer. A lot of air is accordingly needed in these areas. The increased impedance offered by the garbage resting there on the other hand forces the primary air out of the nips and into the regions when the layer is thin and loose, at the edges of the grate for example.